Selective signaling system



Dec. 30, 1941. 1 D. s. HULFISH 2,268,335

SELECTIVE:SIGNALING SYSTEM Filed Jan. 12, 1939 TO STATIONS 32 STATION A) 30 0 AND E f" Ll:

WA 7 I I M42 i I 9: 4e 5o /24 i g 3 FIG. 2 2

INVENTOR.

DAVID S. HULFISH Patented Dec. 30, 1941 SELECTIVE SIGNALING SYSTEM David S. Hulfish, Chicago, 111., assignor to Teletype Corporation, Chicago, Ill., a corporation of Delaware Application January 12, 1939, Serial No. 250,485

9 Claims. AC1. 1782) The present invention pertains to telegraph communication systems and more particularly to telegraph systems including a line having a plurality of serially connected stations each of which is provided with connective apparatus for selective communicative interconnection of any of the stations under control of any one of the stations.

An object of the invention is the provision in a telegraph system wherein the stations are serially connected of a mechanism for facilitating selection and subsequent communication among stations.

A feature of the invention resides in organizing the circuit system of each station in such manner that a selectively established communicative connection is protected against interruption by any accidental or inadvertent act at an unselected and therefore noncommunicative station, yet in such manner that an unselected station may interrupt an established communicative connection but may observe the nature of an established communication before deciding to interrupt the established communication.

When a plurality of stations are connected upon a line serially without selective devices, all stations necessarily respond to all transmitted messages, although some messages may have no interest for some of the stations. When recording instruments are utilized, the noted condition obviously results at every station in a complete record of the trafiic on the line, producing at every station a mass of records in which messages for that station tend to be obscured or confused by messages which have interest only to other stations.

To relieve the confusion caused by useless records, there has been adopted the expedient of providing selective devices at each station for suppressing at each station those messages which have no interest to that station. It is to such modified systems that this invention specifically applies.

In such systems, it is customary to render all stations normally inert or nonresponsive to signals of intelligence communication, but responsive to signals of selection, any transmission of message signals being uniformly preceded by transmission of selective signals which cause to be connected to the line circuit or otherwise render responsive to line signals the recording elements of those stations identified by the selective signals. During message transmission in such a system, each station may be classified as selected, or as unselected, only the selected stations being responsive to communicative signals.

When a communicative condition has been established in such a system, it may be found that unselected stations are wholly disabled and without power to obtain use of the line circuit in any way, thus attaining a degree of secrecy for the messages by limiting the recording function to the selected station or stations. This may be the result of design exemplified, for example, in Patent No. 2,152,010, granted March 28, 1939 to Walter J. Zenner.

In the case that a user of such a system has chosen the selective feature solely for the attainment of simplification of office records, then at times it may be found an inconvenience that an unselected or locked out station having an important message cannot obtain service over a line which is instantly occupied with commercial or public messages.

The above and other objects of the invention are attained by providing a manual monitor key at each station by means of which an operator at an unselected station may render at will the recorder of the station responsive to the signals of an established communication, thereby observing the subject matter being transmitted. When an unselected station thus is qualified by an operator to be responsive to the line signals, the condition of the station equipment according to this invention is the same as though the station had been selected originally as a party to the communication. The station is empowered to transmit as well as to record, and it is subject to signals in the line circuit for terminating the communicative condition. A further manual key is provided for returning the monitoring station to unselected condition, this further key finding utility in the event that the operator decides not to interrupt the established communication. Provision is made also for avoiding the operation of answer-back signal devices under such conditions.

A more complete understanding of the invention will be obtained by the following description, taken in connection with the accompanying drawing, wherein,

Fig. 1 illustrates a circuit system of a telegraph station embodying the invention, and

Fig. 2 illustrates a mechanical detail of apparatus of which the electrical features are embodied in the circuit system of Fig. 1,

The present invention is exemplified in the drawings in the form of an improvement to a telegraph system of apparatus assembled according to the teachings of the Zenner patent identifled above.

Referring to the drawing for an understanding of structural details and giving attention first to Fig. 2, the mechanism illustrated therein is excerpted from the disclosure of Patent No. 1,904,164 issued to S. Morton et al., specifically Fig. 27 thereof. In Fig. 2, an operating code signal member H is tensioned by spring |2 and is restrained by an operating bail l3. Six rocking vanes M are positioned to obstruct or to permit the rotation'of member ll upon its pivot l5. Obstruction is effected when any vane is in other than its permissive code signal position as determined by the location of notches in the code signal member H. An electrical contact spring I6 is moved by member when that member is operated, and a switching function is performed among contacts of spring l3 and contacts of its associated fixed contact members I! I and [8.

In each station equipment, three code signal members such as H are-provided to operate re spectively three sets of contact springs in the manner of contacts 16, I7, and I8, Fig. 2, indicated at 2|, 2'3, and 24 for each station. In the case of contact device 2|, the controlling code signals are combinationally variant in the notches presented to the vanes M for the several stations respectively and constitute the variant calling signals for the several stations individually. Contact devices 23 are controlled by code members l which are combinationally alike at all stations and are responsive to a stop code signal carriage return, while contact devices 24 are controlled by other code members II which are combinationally alike at all stations and are responsive to lockout code signal space.

Also in each station equipment, Fig, 1, there is included manual key H] of time control type adjusted for a determined time period in operation. Upon manual operation and release of the key IS, the contact members open the electrical circuit of the key and subsequently close after a time period determined by preliminary adjustment of the timing elements. Key I9 is adjusted to hold line circuit 3| open for a time period suf-' ficient to deenergize all slowto-release relays 3%, there being such a relay at each station and to permit release of their armatures.

Complete recorders, one for each station, each driven by a motor 4| and each embodying three devices according to Fig. 2, are indicated by the selector magnet 35 under control of line relay 34 which may be either polar or neutral.

Complete transmitters, of keyboard type, one for each station, are indicated at 32. Each such transmitter is provided with an answer-back attachment indicated generally at 43 and comprising an answer-back magnet 45 with armature pivoted at 45 and associated mechanically with a key lever 44 of the keyboard transmitter 32, the answer-back key levers being variant at the several stations, the magnet 45 preferably acting upon key levers as follows: At station A upon key lever B, at station C (not shown) upon key lever D, and. at station E (not shown) upon key lever F, and so on, the alphabet being exhausted when 13 stations have been designated alphabetically. The armature of magnet 45 has an extending member with a distal end positioned above a key lever 44 of the transmitter 32, which member when operated through electromagnetic operation of the armature, will strike the key lever 44 with full effect of depressing the key lever by an operator, resulting in transmission of a code signal identifying the key lever and effective to print a character corresponding thereto upon all recorders connected in the line circuit. The character printed upon all recorders in response to electromagnetic operation of the key lever identifies the answer-back transmitting station to all operators at stations.

There are also provided at each station a slowto-release relay 36, a motor control relay 31, a call responsive relay 38, and a busy signal relay 39 together with a white signal lamp 42 and a red signal lamp 43, the white lamp 42 constituting a visual signal indicating that the station is qualified for telegraphic reception and the red lamp 43 indicating, when illuminated, that the line 3| is held in a completed communicative condition. Circuit connections of the several described structural elements will be developed in a description of operation, to follow. The line circuit 3| extends in series through all stations, station A solely being shown, the letter which identifies the station serving also to identify the calling code signal in response to which the station can be selected or qualified for communication.

To the structure above described illustrating the identified Zenner patent, there are added for purpose of illustrating the present invention two manual keys 48 and 50. A manual monitor key 48 is connected to positive battery and to the windings of motor control relay 31 and calling relay 38 and has also a breaking contact connected to a conductor leading to winding of magnet 46. A further manual release key 50 has breaking contacts connected respectively in circuit of the winding of relay 38 and in the holding circuit of motor control relay 31.

Operation of the system is as follows in which it will be assumed that station A is calling station C for communication exclusive of station E.

An operator at station A first operates the time key l9. This deenergizes all line relays 3|! and 34 and effects release of armatures of all slow-to-release relays 38 at each station with resultant energization of motor control relays 31 at all stations, each relay 3'! through its lower armature setting up its own holding circuit and a circuit for lamp 42 through contacts of key 50 and of devices 24 and 23 to positive battery, and each relay 3? through its upper armature also setting up the condition of starting and continuing operation of all motors 4| atall stations. The printing telegraph receivers of which magnet 35 constitutes a part are now in condition to receive message signals. Automatic reclosing of key l9 reenergizes relays 30, 34, and 36 at each station.

The operator at station A next transmits by keyboard transmitter 32 the call letter A for qualifying station A, which operates contact device 2| at station A but not at any other station because only at station A is the code lever N, Fig. 2, pertaining to device 2|, Fig; 1, cutfor the code signal A but the character A is printed at all stations in response to the calling code signal over the line 3|. Responsive to operation of the contact device 2| at station A, the call responsive relay 38 thereat is energized and forms its holding circuit through its own contact and the front contact and armature of relay 36 to grounded positive battery. Answer-back magnet 46 at station A also is energized momentarily over a circuit through lowest armature and back contact of relay 39 and contact device "2| to battery. Magnet 46 attracts its armature momentarily and depresses the key lever 44 momentarily with the same effect as manually depressing the key B. Responsively, the keyboard transmitter 32 transmits the code signal B upon the line 3| thus completing a recording at all stations of AB.

Operator at station A now operates key C of the keyboard thus transmitting the code signal for station C to which the contact device 2| at station C responds but not at any other station, because only at station C is there found a code lever cut for code signal C, but the character C is printed at all stations, and in response to contact device 2| at station C, the call signal relay 38 at station C responds and forms its holding circuit through relay 38 at station C, and answer-back magnet 46 responds and operates a key lever of the keyboard at station C, but in this instance, it is key lever D resulting in the operation of keyboard transmitter 32 at station C to transmit the code signal D upon line circuit 3| resulting in printing D at all stations and thus completing a recording of ABCD at all stations.

Operator at station A having qualified stations A and C as desired, now disqualifies all other stations by striking the keyboard space bar which transmits space code signal upon line 3| which operates momentarily the contact device 24 producing four results. First, at all stations relay 39 is energized over an obvious circuit through the upper contact of device 24 and forms its holding circuit through the front contact of relay 36 to grounded battery. Second, the holding circuit described above for relay 3! at nonqualified station E is broken by contact device 24, the relay is deenergized and releases its armature to stop its motor 4| and to extinguish its white lamp 42. Third, energized busy relays 39 also illuminate the red busy lamps 43 at all stations whether a station has been selected or excluded. Fourth, upper contacts of relay 39 and upper contacts of unenergized call signal relay 38 close a short circuiting shunt 49 around transmitter 32 and key l9 rendering those instrumentalities electrically ineffective even if manually operated.

However, at selected and qualified stations A and C while the contact device 24 breaks the original holding circuit of motor control relay 31, the relay 31 is not deenergized at this time because a further holding circuit for this relay has been set up and now continues through contacts of relay 31, contacts of key 50, and contacts of energized call signal relay 38 to ground. It results, therefore, that motors 4| are stopped at all unqualified stations; namely, station E and any other stations connected to the line 3|.

At each station there now has been printed upon the record ABCD followed by a word space indicating that station A has been calling, that station C has been called, and that all other stations have been excluded. The white lamp and the red lamp are glowing at each qualified station While the red lamp is glowing alone at excluded stations. The excluded stations are provided with th knowledge of the identity of the stations which are using the line circuit 3|. The stations have a further supervisory function which may be exercised by operation of manual key 48.

An operator at an excluded station desiring to dispatch a message over line 3| may operate key 48 momentarily at such station, thereby energizing the motor control relay 3'! and call relay 38 at that station over obvious circuits, and each relay closes its holding circuit as above described.

at each excluded station Rotation of the motor renders effectively operative the recorder 35, while the breaking of the shunt 49 at contacts of relay 38 renders efiective the keyboard transmitter 32 and the manual key l9. The operator at the unselected station now may judge of the relative importance of the proposed message over the probable importance of the message being currently transmitted be tween or among the prior communicating stations and which now is being recorded at the conditionally qualified station, and the operator may interrupt the said communication by operating key I9 to restart all stopped motors and then may set up any desired connection.

Should the operator decide not to interrupt the existing connection, a momentary operation of manual key 58 will interrupt the described holding circuits of relays 31 and 38 and will restore the station apparatus to normal unselected condition.

At the close of the communication period, station A or any operating station may operate key I9 which will deenergize and release all slowto-release relays 36 at all stations which, in turn, will interrupt the holding circuits of all operated relays 38 and 39 at all stations and will reenergize motor control relays 31 and will restart motors 4| at unselected stations. The operator then may transmit a stop code signal carriage return which will operate contact device 23 at all stations to interrupt the holding circuit of motor control relay 3! at all stations, thus stopping all motors, extinguishing all lamps, and restoring all apparatus to its normal condition of idleness and readiness for further service.

The present invention having been described above in connection with illustration of specific embodiments thereof now will be considered more generally and will be definitely pointed out in the claims without limitation to the specific form used above for illustration.

What is claimed is:

1. In a station selective telegraph system, a plurality of stations, a line associated with all stations, selector relays responsive to line signals to associate said stations communicatively with said line, further relays responsive to line signals to disable said selector relays, and manually operable keys associated with said selector relays to energize said selector relays.

2. In a station selective and intercommunicative telegraph system, means to establish in selected stations of said system a station selecting condition including selective devices responsive to keyboard control, means to terminate said selecting condition in said selected stations, and means manually operable at an unselected station to change said station from unselected condition into selected condition responsive to station release operation by said second mentioned means.

3. In a station selective telegraph system, a plurality of stations, permutation code transmitters at said stations, a line interconnecting all of said stations, station selective relays at said stations, each of said relays responsive to any of said transmitters and effective when operated to associate one of said stations to said line for communication, further relays at said stations responsive to said transmitters and effective when operated to prevent operation of unoperated ones of said station selective relays, and manually operable keys at said stations connected to said station selective relays and each effective to operate a station selective relay to connect its station to said line for communication. despite prior operation: of said further relays.

4. In a station selective telegraph system, a line conductor, a plurality of stations on said line conductor for telegraphic communication, a line signal and code selector responsive relay at each station for conditioning said stations selectively for communication, and means comprising a manual key at each of said stations to which said relay is directly responsive operative after a station has been rendered unresponsive through operation of said code selector for rendering said station responsive through the operation of said relay to code signals transmitted over said line.

5. In a station selective telegraph system, a line conductor, a plurality of stations connected to said line conductor for telegraphic communication, a line signal and code selector responsive means at each station for qualifying said stations for communication, means for disqualifying certain of said stations for communication, and manually operable means at each station operative to operate said code selector responsive means to qualify for communication during the communication of previously qualified stations a disqualified station.

6. In a station selective telegraph system, a plurality of stations, a line associated with all said stations, selection controlling relays at a station energizable in one combinational condition in response to line signals to condition said station for communication and energizable alternatively in another combinational condition in response to line signals to prevent communication to said station over said line, and a manual key connected to circuits of said relays and effective upon momentary operationto change the condition of said selection controlling relays'from said later mentioned combinational condition into said first-mentioned combinational condition.

'7. In a station selective telegraph system, a plurality of stations, a line associated with all of said stations, station selection means at a station operable into one condition in response to line signals to qualify said station for communication and operable alternatively into another condition in response to line signals to prevent qualification of said station for communication, 7

and manually operable means for changing the condition of said selection means from said later mentioned condition into said first-mentioned condition.

8. In a station selective telegraph system, a plurality of stations, a line associated with all of said stations, station selection means at a station operable into one condition in response to line signals to qualify said station for communication and operable alternatively into another condition in response to line signals to prevent qualification of said station for communication, and manually operable means for changing the condition of said selection means from either mentioned condition into the other mentioned condition.

9. In a station selective telegraph system, a plurality of stations, a line associated with all tations, selector relays responsive to line signals to condition said stations for communication over said line, further relays responsive to line signals to disable said selector relays, and manually operable keys associated with said selector relays to energize and to deenergize said selector relays.

DAVID S. HULFISI-I. 

